Vow. 2] Torrey.—The Behavior of Corymorpha. 335 
Two conclusions which were formerly held, later experiments 
have shown to have been founded on data which were mislead- 
ing owing to the conditions of experimentation. The first was 
that a change in the polarity of a region is accompanied by a 
change in the reactions of the axial cells in this region. The 
second was that, regardless of the point at which it is supported, 
whether proximally or distally, the stem would orient itself ver- 
tically, distal end uppermost. These results were obtained on 
individuals which had been kept in the laboratory during the 
warm days of summer for a week or ten days, and did not be- 
have with the constancy or the precision which characterize the 
actions of the individuals observed last March. The latter were 
used for experimentation immediately upon their capture, and 
were kept under conditions which permitted a vigorous, healthy 
existence. 
With regard to the first conclusion, it may be said that while 
such a change of polarity as heteromorphosis of the proximal 
end of a stem segment would be accompanied by an upturning 
of this end, the result would not be achieved by a change in the 
reactions of the axial cells in this region. The essential factor 
lies rather in the relation of the region in question to the sub- 
stratum. In studying the regeneration of Corymorpha, the ob- 
servation was frequently made that from pieces resting on the 
floor of the aquarium, cut from the distal half of a stem, U- 
shaped figures would be formed, fastened to the floor by the 
loop, the two arms extending vertically upward, each crowned 
with sets of developing tentacles. By the side of these hetero- 
morphic pieces were many others fastened to the substrate by 
one end, which possessed an. incipient holdfast, the other end 
developing tentacles. In both cases, the behavior of the axial 
cells was constant; the cells nearer the center of the earth were 
relatively larger than those on the other side of the stem. The 
proximal ends of the pieces which developed holdfasts remained 
lowermost merely because they were adhesive and clung to the 
substrate, which the distal ends could not do. 
This fact appeared distinctly in the results of my recent 
experiments bearing directly upon the second conclusion stated 
